Configuring Disk Mirroring on the Cisco ASR 9000 Series Router

For complete descriptions of the commands listed in this module, see Related Documents. To locate documentation for other commands that might appear in the course of performing a configuration task, search online in Cisco ASR 9000 Series Aggregation Services Router Commands Master List.

Disk Mirroring Prerequisites

Before enabling disk mirroring, the following conditions must be met:

You must be in a user group associated with a task group that includes the proper task IDs. The command reference guides include the task IDs required for each command. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The secondary storage device specified for the mirroring must be installed in the same node as the primary boot device. The supported storage devices are disk0: and disk1:.

The secondary storage device must be the same size or larger than the designated primary storage device.

The secondary storage device must be partitioned.

Note

The primary partition on the secondary storage device must be large enough to contain all data on the primary boot device. This can be an issue if the primary boot device has not yet been partitioned. For example, in the situation where both the primary boot device and the secondary storage device are 1 GB in size, the primary boot device contains 950 MB of data, and the secondary storage device is already partitioned to 800 MB in the primary partition and 200 MB in the secondary partition. In such a case, the 950 MB of data from the primary boot device does not fit on the secondary storage device because of the partition. Such a configuration is rejected and an error is displayed. You need to replace the secondary storage device with a higher capacity device. For information about disk partition sizes, see Related Topics.

Note

Although compactflash: can be used as the secondary device on a Performance Route Processor (PRP–2), there is an issue with the ROM Monitor not being able to boot the minimum boot image (MBI) from the secondary device if the device is not disk0: or disk1:. In such a situation, you would need to go into ROMMON mode and boot the PRP-2 manually using the MBI on the compactflash:.

Information About Disk Mirroring

The route switch processor (RSP) card has a primary storage device that is used to store installation packages and configuration files. This primary storage device is referred to as the primary boot device and is essential for booting the RSP and its normal operation.

Disk mirroring replicates the critical data on the primary boot device onto another storage device on the same RSP, henceforth referred to as the secondary device. If the primary boot device fails, applications continue to be serviced transparently by the secondary device, thereby avoiding a switchover to the standby RSP. The failed primary storage device can be replaced or repaired without disruption of service.

Disk mirroring should only mirror critical data on the primary boot device onto a secondary storage device and not any noncritical data such as logging data. To separate critical data from noncritical data, the disk devices need to be partitioned. Disk0: is partitioned to disk0: and disk0a:; disk1: is partitioned to disk1: and disk1a:. Disk0: and disk1: are used for critical data, whereas disk0a: and disk1a: are used for logging data and other noncritical data. Before you can configure disk mirroring on the RSP, you must have partitioned the secondary storage device. The sizes of disk partitions are related to the total disk size, and are provided in Table 1.

Table 2 Size of Disk Partitions in Relation to Size of Disk

Size of Disk

Primary Partition Percentage

Secondary Partition Percentage

less than 900 MB

Partitioning not supported

Partitioning not supported

900 MB to 1.5 GB

80%

20%

1.5 GB to 3 GB

60%

40%

more than 3 GB

50%

50%

How to Enable Disk Mirroring

The tasks in this section describe how to enable and manage disk mirroring.

Enabling Disk Mirroring

Complete the following instructions to enable disk mirroring. After disk mirroring is configured, if there is a fault on the primary boot drive or it cannot be accessed for any reason, control is automatically transferred to the secondary storage device.

SUMMARY STEPS

1.format secondary-device partition [locationnode-id]

2. Remove any noncritical data from the primary boot device.

3.configure

4.mirror locationnode-idPrimary-deviceSecondary-device

5.Use one of these commands:

end

commit

6.showmirror [locationnode-id]

7.mirrorverifylocationnode-id

DETAILED STEPS

Command or Action

Purpose

Step 1

format secondary-device partition [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# format disk1: partition

Partitions the secondary storage device into two partitions.

If the device is already partitioned, you do not need to perform this step.

Step 2

Remove any noncritical data from the primary boot device.

The primary boot device should contain installation packages and configuration files only. Log files can be copied to the “a” partition of the secondary device, for example disk1a: .

Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

Use the commit command to save the configuration changes to the running configuration file, and remain within the configuration session.

Step 6

showmirror [locationnode-id]

Example:RP/0/RSP0/CPU0:router# show mirror location 0/ rsp0/cpu0

Displays disk mirroring information for an RSP node. It also provides the status of the synchronization between the primary and secondary devices.

Step 7

mirrorverifylocationnode-id

Example:RP/0/RSP0/CPU0:router# mirror verify location 0/ rsp0/cpu0

Verifies disk synchronization for disk mirroring on an RSP node.

Replacing the Secondary Mirroring Device

Follow this procedure if you need to replace the secondary boot device used in the disk mirroring process.

SUMMARY STEPS

1.show mirror [locationnode-id]

2.mirror pause [locationnode-id]

3.show mirror [locationnode-id]

4.unmountsecondary-device [locationnode-id]

5.Remove the device and insert a new device.

6.format secondary-devicepartition [locationnode-id]

7.show media [locationnode-id]

8.mirror resume [locationnode-id]

9.show mirror [locationnode-id]

DETAILED STEPS

Command or Action

Purpose

Step 1

show mirror [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# show mirror

Verifies that mirroring is active. In the output, the Current Mirroring State should be redundant.

Step 2

mirror pause [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# mirror pause

Temporarily pauses disk mirroring.

Step 3

show mirror [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# show mirror

Verifies that mirroring has paused. In the output, the Current Mirroring State should be paused.

Step 4

unmountsecondary-device [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# unmount disk1:

Unmounts the secondary device.

Step 5

Remove the device and insert a new device.

Step 6

format secondary-devicepartition [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# format disk1: partition

Formats the device.

Step 7

show media [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# show media

Verifies that the device is formatted. The output should display the device that you formatted.

Step 8

mirror resume [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# mirror resume

Resumes mirroring.

Step 9

show mirror [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# show mirror

Verifies that mirroring has restarted. In the output, the Current Mirroring State should be Syncing.

It can take 15 to 30 minutes for the mirroring process to complete. The exact time depends on the number of packages or files on the boot device. When the mirroring is complete, the Current Mirroring State should be Redundant.

Replacing the Primary Mirroring Device

In the event that your primary boot disk is defective and you need to replace it while disk mirroring is enabled, perform this task.

SUMMARY STEPS

1.show mirror [locationnode-id]

2.configure

3.mirror locationnode-idPrimary-deviceSecondary-device

4.Use one of these commands:

end

commit

5.show mirror [locationnode-id]

6.mirror pause [locationnode-id]

7.show mirror

8.unmountsecondary-device [locationnode-id]

9.Remove the device and insert a new device.

10.show media [locationnode-id]

11. (Optional) format secondary-devicepartition [locationnode-id]

12.mirror resume [locationnode-id]

13.show mirror [locationnode-id]

14.configure

15.mirror locationnode-idPrimary-deviceSecondary-device

16.show mirror [locationnode-id]

DETAILED STEPS

Command or Action

Purpose

Step 1

show mirror [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# show mirror

Verifies that mirroring is in the redundant state. In the output, the Current Mirroring State should be redundant. If mirroring is not in the redundant state, you cannot proceed with the procedure. You must wait until mirroring is in the redundant state.

Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

Use the commit command to save the configuration changes to the running configuration file, and remain within the configuration session.

Step 5

show mirror [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# show mirror

Verifies that the primary device is now the secondary device and vice versa. In the output, if disk0: was the primary disk that you want to replace, it should now be listed as the secondary device.

Step 6

mirror pause [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# mirror pause

Temporarily pauses disk mirroring.

Step 7

show mirror

Example:

RP/0/RSP0/CPU0:router# show mirror

Verifies that mirroring has paused. In the output, the Current Mirroring State should be paused.

Step 8

unmountsecondary-device [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# unmount disk1:

Unmounts the secondary device which is the device that you want to replace. Initially, this was the primary device.

Step 9

Remove the device and insert a new device.

Step 10

show media [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# show media

Verifies that the new disk is partitioned. You should see that the new device is mounted. If the new device is not partitioned, format the device as indicated in the next step.

Step 11

format secondary-devicepartition [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# format disk1: partition

(Optional)

Formats the device. You only need to perform this step if the new device is not partitioned.

Step 12

mirror resume [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# mirror resume

Resumes mirroring.

Step 13

show mirror [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# show mirror

Verifies that mirroring has restarted. In the output, the Current Mirroring State should be Syncing.

It can take 15 to 30 minutes for the mirroring process to complete. The exact time depends on the number of packages or files on the boot device. When the mirroring is complete, the Current Mirroring State should be Redundant.

Swaps the device roles back so that the newly inserted device becomes the primary device.

Step 16

show mirror [locationnode-id]

Example:

RP/0/RSP0/CPU0:router# show mirror

Verifies that the new device is now the primary device.

Configuration Examples for Enabling Disk Mirroring

Enabling Disk Mirroring: Example

In the following example, disk mirroring is enabled on a router:

format disk1: partition
This operation will destroy all data on "disk1:" and partition device.
Continue? [confirm] y
Device partition disk1: is now formated and is available for use.
configure
mirror location 0/0/cpu0 disk0:disk1:
commit

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RFCs

Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

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